transmission between neurons Flashcards
how do neurones send messages?
via synaptic transmission
outline the steps of transmission between neurones
- neurotransmitters are released from one neurone
- neurotransmitters travel across synaptic junction/cleft
- neurotransmitters to post-synaptic receptors of another neurone
- initiates a reaction
- results in post-synaptic potentials
what are neurotransmitters?
chemical messengers that travel from neurone to neurone
what is the synaptic cleft?
gap between two neurones
gap between the terminal button of the presynaptic neurone and the postsynaptic membrane
how big is the synaptic cleft?
20 nanometres
what are synaptic vesicles?
contains neurotransmitters
binds to receptor, releasing membrane
outline the process of synaptic transmission
- action potential at terminal button
- this causes calcium channels to open
- calcium ions enters terminal button
- calcium ions causes vesicle to fuse with membrane
- resulting in pores opening
- neurotransmitters are released into synaptic cleft via process of exocytosis
- neurotransmitter diffuses across synaptic cleft
- neurotransmitter binds to postsynaptic membrane
- causing postsynaptic channels to open
- flow of ions result in excitatory / inhibitory post synaptic potentials
what effect does neurotransmitters binding to post-synaptic membrane have on PSP?
- binding alters the membrane potential of the post synaptic membrane
- this results in either an excitatory postsynaptic potential (a PSP that makes it more likely to fire an action potential)
- or results in an inhibitory postsynaptic potential (a PSP that makes it less likely to generate an action potential)
how does a neurotransmitter bind to binding site on post-synaptic membrane?
lock and key
what effects the postsynaptic potential?
which ion channel (lock) is open is what will determine the PSP
identify two types of receptors
1/ ionotropic receptor
2/ metabotropic receptor
explain what an ionotropic receptor is
- type of receptor containing binding site AND ion channel
- opens when molecule attaches to binding site
explain what a metabotropic receptor is
- contains binding site
- initiates chain reaction
- chain reaction will open ion channels
- requires energy
- postsynaptic potential is slower than PSPs produced by ionotropic receptors
define ‘reuptake’
this is where transmitter is taken back up by presynaptic terminal via transporter molecules
define ‘enzymatic deactivation/degradation’
this is where transmitter is broken down by an enzyme
define ‘enzymatic deactivation/degradation’
this is where transmitter is broken down by an enzyme
what are excitatory PSPs?
PSPs that increase likelihood of neurone firing
what are the inhibitory PSPs?
PSPs that decrease the likelihood of neurone firing
- these do not always inhibit behaviour
- inhibition of inhibitory neurones = more likelihood of behaviour
- excitatory of inhibitory neurones = less likelihood of behaviour
what is integration?
summation of PSPs in control of neurone firing = integration
ability to integrate multiple PSPs at multiple synapses = summation
outline the neurotransmitter GABA
- most abundant inhibitory neurotransmitter
- reduces chance of neuronal firing
- important role in brain development
outline the neurotransmitter Glutamate
- most abundant excitatory neurotransmitter
- can bind to number of receptors
- important in learning and memory
outline the neurotransmitter Acetylcholine (ACh)
- found in CNS and PNS
- works primarily in muscles
- helps translate our intentions to move into actions
outline the neurotransmitter dopamine
- pleasure chemical
- released when mammals receive reward
- has responsibility for motor control
outline the neurotransmitter serotonin
- regulation of mood
- help manage eating, sleeping, memory
- lack of serotonin = depression
what is an antagonist
drug that blocks neurotransmitters
what is an agonist
- drug that mimics neurotransmitter
- enhances synapse function
